A new cell search scheme based on cell-clustering for UDN

Since user equipment (UE) has to obtain the cell identification (cell ID) and timing information to start the communication with base station, cell search is the initial step in cellular systems. The research of 5G has been started to improve the performance of wireless communication. A new scenario named ultra-dense network (UDN) has been introduced and there will be more access nodes per unit area. However, with the distribution of small cells gets more complicated and the interference is stronger, cell search will be a big challenge. In Long Term Evolution (LTE) of 4 G, two signals named primary synchronization signal (PSS) and secondary synchronization signal (SSS) are designed for cell search. Correct detection of synchronization signals makes UE be able to get the frame boundary and Cell ID. However, the detection accuracy will be poor when the cell density grows. Focusing on UDN scenario, we give a definition of cell cluster and design new synchronization signals. Moreover, a new cell search scheme based on the redesigned signals is presented. Simulation is conducted to evaluate the detection accuracy of the new scheme. The result presents that the performance of the new scheme is much better than the existing scheme in LTE.